Vehicular wiring systems have become increasingly complicated in recent years, due both to the proliferation of various electrically operated options on vehicles, and also to the increasing sophistication of electromechanical devices. Many of the connector terminals used in the automotive field must be capable of withstanding heavy current loads, such as the heavy output cables connecting generators, alternators and batteries. Moreover, anticipated reintroduction of electric powered vehicles to the marketplace will require even more heavy duty current connectors. Of course, the "under the hood" environment in which these connector terminals are employed puts a great deal of both mechanical and thermal stress on the connections, themselves. Hence, the mating members of electrical connectors of this type must be held together with a firm grip so that the connection does not fail during normal usage. Additionally, these connections must be relatively easy to make; that is, it is highly desirable that one member of the connector terminal be readily insertable into its mating member. The connectors also must be heavy duty to withstand the high current loads, and must also provide adequate electrical contact between the prong and the socket. It is also important that members of a connector pair be uniquely matable so as to prevent the inadvertent misconnection of non-corresponding electrical terminals, an event which could lead to fire, injury or other severe damage in a high-current system.
One class of electrical connector which has evolved in recent years is known as a low insertion force connector. One familiar type of such connector is called a zero insertion force connector. These connectors are particularly useful in applications where the electrical connectors need to be repeatedly coupled and decoupled, such as in vehicular uses. The low insertion force connectors, while utilizing spring loaded contacts in one or both member, s of the mating pairs, have provisions wherein the contact pressure may be temporarily withheld during coupling or decoupling. In particular, a spring loaded female receptacle which engages a solid pin member has provisions inside its socket for temporarily enlarging its effective inside diameter; thus, it will readily disengage the pin during insertion or removal.
An example of such a low insertion force connector is shown in U.S. Pat. No. 5,154,626 wherein the means for temporarily enlarging the socket diameter includes a double helix having two interleaved, helical coils formed into an integral link or loop transversing the coils diametrically and connecting them together. The inside diameter of the double helix may be varied by rotationally driving the closed end of the double helix. The resilience of the wire material spring loads the double helix in a manner which provides secure clamping engagement with the mating pin, along with the ability to release the double helix for insertion or removal of the pin by applying torque to the loop end. While this type of low insertion force connector is highly effective in function, it is also mechanically complicated and expensive to produce.
A simpler and less expensive low insertion force connector is described in U.S. Pat. No. 4,657,335 wherein a radially resilient cage is disposed inside the terminal socket, the cage being constructed from a sheet metal stamping. The stamping is made by cutting longitudinal, spaced, parallel slots in a rectangular blank. The slotted blank is then rolled up into cylindrical form, and inserted into the socket after being given a partial twist at the ends so that the slots are helically aligned inside the socket. The low insertion force connector disclosed in the '335 patent has been shown to be an effective, inexpensive and easy to use connector in various applications.
The present invention is to a connector terminal specifically adapted for high current requirements which is particularly easy to couple and decouple, which provides reliable, positive force connection between the terminal members and which ensures the connection of the right leads to the right receptors in the terminal, even in a variety of wiring configurations.